Re: [Intel-gfx] [PATCH v4] drm/i915: Handle RC6 counter wrap
Quoting Tvrtko Ursulin (2018-02-08 15:46:38)
> From: Tvrtko Ursulin
>
> We can implement limited RC6 counter wrap-around protection under the
> assumption that clients will be reading this value more frequently than
> the wrap period on a given platform.
>
> With the typical wrap-around period being ~90 minutes, even with the
> exception of Baytrail which wraps every 13 seconds, this sounds like a
> reasonable assumption.
>
> Implementation works by storing a 64-bit software copy of a hardware RC6
> counter, along with the previous HW counter snapshot. This enables it to
> detect wrap is polled frequently enough and keep the software copy
> monotonically incrementing.
>
> v2:
> * Missed GEN6_GT_GFX_RC6_LOCKED when considering slot sizing and
>indexing.
> * Fixed off-by-one in wrap-around handling. (Chris Wilson)
>
> v3:
> * Simplify index checking by using unsigned int. (Chris Wilson)
> * Expand the comment to explain why indexing works.
>
> v4:
> * Use __int128 if supported.
>
> Signed-off-by: Tvrtko Ursulin
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94852
> Cc: Chris Wilson
> Reviewed-by: Chris Wilson # v3
> Cc: Ville Syrjälä
> ---
> drivers/gpu/drm/i915/i915_drv.h | 2 ++
> drivers/gpu/drm/i915/intel_pm.c | 72
> +++--
> 2 files changed, 64 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index ad1fc845cd1b..28a2671a26c7 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -946,6 +946,8 @@ struct intel_rps {
>
> struct intel_rc6 {
> bool enabled;
> + u64 prev_hw_residency[4];
> + u64 cur_residency[4];
> };
>
> struct intel_llc_pstate {
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 41f26ab46501..24d9423c5f9e 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -9417,15 +9417,16 @@ static u64 vlv_residency_raw(struct drm_i915_private
> *dev_priv,
> const i915_reg_t reg)
> {
> u32 lower, upper, tmp;
> - unsigned long flags;
> int loop = 2;
>
> - /* The register accessed do not need forcewake. We borrow
> + /*
> +* The register accessed do not need forcewake. We borrow
> * uncore lock to prevent concurrent access to range reg.
> */
> - spin_lock_irqsave(&dev_priv->uncore.lock, flags);
> + lockdep_assert_held(&dev_priv->uncore.lock);
>
> - /* vlv and chv residency counters are 40 bits in width.
> + /*
> +* vlv and chv residency counters are 40 bits in width.
> * With a control bit, we can choose between upper or lower
> * 32bit window into this counter.
> *
> @@ -9449,29 +9450,54 @@ static u64 vlv_residency_raw(struct drm_i915_private
> *dev_priv,
> upper = I915_READ_FW(reg);
> } while (upper != tmp && --loop);
>
> - /* Everywhere else we always use VLV_COUNTER_CONTROL with the
> + /*
> +* Everywhere else we always use VLV_COUNTER_CONTROL with the
> * VLV_COUNT_RANGE_HIGH bit set - so it is safe to leave it set
> * now.
> */
>
> - spin_unlock_irqrestore(&dev_priv->uncore.lock, flags);
> -
> return lower | (u64)upper << 8;
> }
>
> u64 intel_rc6_residency_ns(struct drm_i915_private *dev_priv,
>const i915_reg_t reg)
> {
> - u64 time_hw;
> +#if IS_ENABLED(CONFIG_ARCH_SUPPORTS_INT128)
> + unsigned __int128 acc;
> +#else
> + u64 acc;
> +#endif
> + u64 time_hw, prev_hw, overflow_hw;
> + unsigned int fw_domains;
> + unsigned long flags;
> + unsigned int i;
> u32 mul, div;
>
> if (!HAS_RC6(dev_priv))
> return 0;
>
> + /*
> +* Store previous hw counter values for counter wrap-around handling.
> +*
> +* There are only four interesting registers and they live next to
> each
> +* other so we can use the relative address, compared to the smallest
> +* one as the index into driver storage.
> +*/
> + i = (i915_mmio_reg_offset(reg) -
> +i915_mmio_reg_offset(GEN6_GT_GFX_RC6_LOCKED)) / sizeof(u32);
> + if (WARN_ON_ONCE(i >= ARRAY_SIZE(dev_priv->gt_pm.rc6.cur_residency)))
> + return 0;
> +
> + fw_domains = intel_uncore_forcewake_for_reg(dev_priv, reg,
> FW_REG_READ);
> +
> + spin_lock_irqsave(&dev_priv->uncore.lock, flags);
> + intel_uncore_forcewake_get__locked(dev_priv, fw_domains);
> +
> /* On VLV and CHV, residency time is in CZ units rather than 1.28us */
> if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
> mul = 100;
> div = dev_priv->czclk_freq;
> + overflow_hw = BIT_ULL(40);
> time_hw = v
Re: [Intel-gfx] [PATCH v4] drm/i915: Handle RC6 counter wrap
On 08/02/2018 15:46, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin
We can implement limited RC6 counter wrap-around protection under the
assumption that clients will be reading this value more frequently than
the wrap period on a given platform.
With the typical wrap-around period being ~90 minutes, even with the
exception of Baytrail which wraps every 13 seconds, this sounds like a
reasonable assumption.
Implementation works by storing a 64-bit software copy of a hardware RC6
counter, along with the previous HW counter snapshot. This enables it to
detect wrap is polled frequently enough and keep the software copy
monotonically incrementing.
v2:
* Missed GEN6_GT_GFX_RC6_LOCKED when considering slot sizing and
indexing.
* Fixed off-by-one in wrap-around handling. (Chris Wilson)
v3:
* Simplify index checking by using unsigned int. (Chris Wilson)
* Expand the comment to explain why indexing works.
v4:
* Use __int128 if supported.
Signed-off-by: Tvrtko Ursulin
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94852
Cc: Chris Wilson
Reviewed-by: Chris Wilson # v3
Cc: Ville Syrjälä
---
drivers/gpu/drm/i915/i915_drv.h | 2 ++
drivers/gpu/drm/i915/intel_pm.c | 72 +++--
2 files changed, 64 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ad1fc845cd1b..28a2671a26c7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -946,6 +946,8 @@ struct intel_rps {
struct intel_rc6 {
bool enabled;
+ u64 prev_hw_residency[4];
+ u64 cur_residency[4];
};
struct intel_llc_pstate {
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 41f26ab46501..24d9423c5f9e 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -9417,15 +9417,16 @@ static u64 vlv_residency_raw(struct drm_i915_private
*dev_priv,
const i915_reg_t reg)
{
u32 lower, upper, tmp;
- unsigned long flags;
int loop = 2;
- /* The register accessed do not need forcewake. We borrow
+ /*
+* The register accessed do not need forcewake. We borrow
* uncore lock to prevent concurrent access to range reg.
*/
- spin_lock_irqsave(&dev_priv->uncore.lock, flags);
+ lockdep_assert_held(&dev_priv->uncore.lock);
- /* vlv and chv residency counters are 40 bits in width.
+ /*
+* vlv and chv residency counters are 40 bits in width.
* With a control bit, we can choose between upper or lower
* 32bit window into this counter.
*
@@ -9449,29 +9450,54 @@ static u64 vlv_residency_raw(struct drm_i915_private
*dev_priv,
upper = I915_READ_FW(reg);
} while (upper != tmp && --loop);
- /* Everywhere else we always use VLV_COUNTER_CONTROL with the
+ /*
+* Everywhere else we always use VLV_COUNTER_CONTROL with the
* VLV_COUNT_RANGE_HIGH bit set - so it is safe to leave it set
* now.
*/
- spin_unlock_irqrestore(&dev_priv->uncore.lock, flags);
-
return lower | (u64)upper << 8;
}
u64 intel_rc6_residency_ns(struct drm_i915_private *dev_priv,
const i915_reg_t reg)
{
- u64 time_hw;
+#if IS_ENABLED(CONFIG_ARCH_SUPPORTS_INT128)
+ unsigned __int128 acc;
+#else
+ u64 acc;
+#endif
+ u64 time_hw, prev_hw, overflow_hw;
+ unsigned int fw_domains;
+ unsigned long flags;
+ unsigned int i;
u32 mul, div;
if (!HAS_RC6(dev_priv))
return 0;
+ /*
+* Store previous hw counter values for counter wrap-around handling.
+*
+* There are only four interesting registers and they live next to each
+* other so we can use the relative address, compared to the smallest
+* one as the index into driver storage.
+*/
+ i = (i915_mmio_reg_offset(reg) -
+i915_mmio_reg_offset(GEN6_GT_GFX_RC6_LOCKED)) / sizeof(u32);
+ if (WARN_ON_ONCE(i >= ARRAY_SIZE(dev_priv->gt_pm.rc6.cur_residency)))
+ return 0;
+
+ fw_domains = intel_uncore_forcewake_for_reg(dev_priv, reg, FW_REG_READ);
+
+ spin_lock_irqsave(&dev_priv->uncore.lock, flags);
+ intel_uncore_forcewake_get__locked(dev_priv, fw_domains);
+
/* On VLV and CHV, residency time is in CZ units rather than 1.28us */
if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
mul = 100;
div = dev_priv->czclk_freq;
+ overflow_hw = BIT_ULL(40);
time_hw = vlv_residency_raw(dev_priv, reg);
} else {
/* 833.33ns units on Gen9LP, 1.28us elsewhere. */
@@ -9483,10 +9509,36 @@ u64 intel_rc6_residency_ns(struct drm_i915_private
*dev_priv,
div = 1;
}
- time_hw = I915_RE
[Intel-gfx] [PATCH v4] drm/i915: Handle RC6 counter wrap
From: Tvrtko Ursulin
We can implement limited RC6 counter wrap-around protection under the
assumption that clients will be reading this value more frequently than
the wrap period on a given platform.
With the typical wrap-around period being ~90 minutes, even with the
exception of Baytrail which wraps every 13 seconds, this sounds like a
reasonable assumption.
Implementation works by storing a 64-bit software copy of a hardware RC6
counter, along with the previous HW counter snapshot. This enables it to
detect wrap is polled frequently enough and keep the software copy
monotonically incrementing.
v2:
* Missed GEN6_GT_GFX_RC6_LOCKED when considering slot sizing and
indexing.
* Fixed off-by-one in wrap-around handling. (Chris Wilson)
v3:
* Simplify index checking by using unsigned int. (Chris Wilson)
* Expand the comment to explain why indexing works.
v4:
* Use __int128 if supported.
Signed-off-by: Tvrtko Ursulin
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94852
Cc: Chris Wilson
Reviewed-by: Chris Wilson # v3
Cc: Ville Syrjälä
---
drivers/gpu/drm/i915/i915_drv.h | 2 ++
drivers/gpu/drm/i915/intel_pm.c | 72 +++--
2 files changed, 64 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ad1fc845cd1b..28a2671a26c7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -946,6 +946,8 @@ struct intel_rps {
struct intel_rc6 {
bool enabled;
+ u64 prev_hw_residency[4];
+ u64 cur_residency[4];
};
struct intel_llc_pstate {
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 41f26ab46501..24d9423c5f9e 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -9417,15 +9417,16 @@ static u64 vlv_residency_raw(struct drm_i915_private
*dev_priv,
const i915_reg_t reg)
{
u32 lower, upper, tmp;
- unsigned long flags;
int loop = 2;
- /* The register accessed do not need forcewake. We borrow
+ /*
+* The register accessed do not need forcewake. We borrow
* uncore lock to prevent concurrent access to range reg.
*/
- spin_lock_irqsave(&dev_priv->uncore.lock, flags);
+ lockdep_assert_held(&dev_priv->uncore.lock);
- /* vlv and chv residency counters are 40 bits in width.
+ /*
+* vlv and chv residency counters are 40 bits in width.
* With a control bit, we can choose between upper or lower
* 32bit window into this counter.
*
@@ -9449,29 +9450,54 @@ static u64 vlv_residency_raw(struct drm_i915_private
*dev_priv,
upper = I915_READ_FW(reg);
} while (upper != tmp && --loop);
- /* Everywhere else we always use VLV_COUNTER_CONTROL with the
+ /*
+* Everywhere else we always use VLV_COUNTER_CONTROL with the
* VLV_COUNT_RANGE_HIGH bit set - so it is safe to leave it set
* now.
*/
- spin_unlock_irqrestore(&dev_priv->uncore.lock, flags);
-
return lower | (u64)upper << 8;
}
u64 intel_rc6_residency_ns(struct drm_i915_private *dev_priv,
const i915_reg_t reg)
{
- u64 time_hw;
+#if IS_ENABLED(CONFIG_ARCH_SUPPORTS_INT128)
+ unsigned __int128 acc;
+#else
+ u64 acc;
+#endif
+ u64 time_hw, prev_hw, overflow_hw;
+ unsigned int fw_domains;
+ unsigned long flags;
+ unsigned int i;
u32 mul, div;
if (!HAS_RC6(dev_priv))
return 0;
+ /*
+* Store previous hw counter values for counter wrap-around handling.
+*
+* There are only four interesting registers and they live next to each
+* other so we can use the relative address, compared to the smallest
+* one as the index into driver storage.
+*/
+ i = (i915_mmio_reg_offset(reg) -
+i915_mmio_reg_offset(GEN6_GT_GFX_RC6_LOCKED)) / sizeof(u32);
+ if (WARN_ON_ONCE(i >= ARRAY_SIZE(dev_priv->gt_pm.rc6.cur_residency)))
+ return 0;
+
+ fw_domains = intel_uncore_forcewake_for_reg(dev_priv, reg, FW_REG_READ);
+
+ spin_lock_irqsave(&dev_priv->uncore.lock, flags);
+ intel_uncore_forcewake_get__locked(dev_priv, fw_domains);
+
/* On VLV and CHV, residency time is in CZ units rather than 1.28us */
if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
mul = 100;
div = dev_priv->czclk_freq;
+ overflow_hw = BIT_ULL(40);
time_hw = vlv_residency_raw(dev_priv, reg);
} else {
/* 833.33ns units on Gen9LP, 1.28us elsewhere. */
@@ -9483,10 +9509,36 @@ u64 intel_rc6_residency_ns(struct drm_i915_private
*dev_priv,
div = 1;
}
- time_hw = I915_READ(reg);
+ overflow
